Nuclear redox signaling

Chrysophanol-mediated trx-1 activation attenuates renal fibrosis through inhibition of the JNK/Cx43 signaling pathway

PURPOSE

This study aimed to investigate the inhibitory effect of chrysophanol on renal fibrosis and its molecular mechanism.

METHODS

Initially, potential targets of chrysophanol were predicted through network pharmacology analysis, and a protein-protein interaction network of these targets was constructed using Venn diagrams and the STRING database. GO enrichment analysis predicted the biological process of chrysophanol in treating renal fibrosis. Subsequently, both in vivo and in vitro experiments were conducted using unilateral ureteral obstruction (UUO) induced CKD mouse model and HK-2 cell model, respectively. In the mouse model, different doses of chrysophanol were administered to assess its renal protective effects through biochemical indicators, histological examination, and immunofluorescence staining. In the cell model, the regulatory effect of chrysophanol on the Trx-1/JNK/Cx43 pathway was evaluated using western blotting and flow cytometry.

RESULTS

Chrysophanol treatment significantly ameliorated renal dysfunction and histopathological damage in the UUO mouse model, accompanied by a reduction in serum oxidative stress markers. Furthermore, chrysophanol markedly upregulated the expression of Trx-1 in renal tissues and inhibited the activation of the JNK/Cx43 signaling pathway. At the cellular level, chrysophanol enhanced the activity of Trx-1 and downregulated the JNK/Cx43 signaling pathway, thereby inhibiting TGF-β induced oxidative stress and cell apoptosis.

CONCLUSION

This study demonstrated a significant inhibitory effect of chrysophanol on renal fibrosis, mediated by the activation of Trx-1 to inhibit the JNK/Cx43 pathway. These findings provide experimental support for the potential use of chrysophanol as a therapeutic agent for renal fibrosis.

Navigating the redox landscape: reactive oxygen species in regulation of cell cycle

Objectives: To advance our knowledge of disease mechanisms and therapeutic options, understanding cell cycle regulation is critical. Recent research has highlighted the importance of reactive oxygen species (ROS) in cell cycle regulation. Although excessive ROS levels can lead to age-related pathologies, ROS also play an essential role in normal cellular functions. Many cell cycle regulatory proteins are affected by their redox status, but the precise mechanisms and conditions under which ROS promote or inhibit cell proliferation are not fully understood.Methods: This review presents data from the scientific literature and publicly available databases on changes in redox state during the cell cycle and their effects on key regulatory proteins.Results: We identified redox-sensitive targets within the cell cycle machinery and analysed different effects of ROS (type, concentration, duration of exposure) on cell cycle phases. For example, moderate levels of ROS can promote cell proliferation by activating signalling pathways involved in cell cycle progression, whereas excessive ROS levels can induce DNA damage and trigger cell cycle arrest or cell death.Discussion: Our findings encourage future research focused on identifying redox-sensitive targets in the cell cycle machinery, potentially leading to new treatments for diseases with dysregulated cell proliferation.

Cognitive Dysfunction and Exercise: From Epigenetic to Genetic Molecular Mechanisms

Maintaining good health is crucial, and exercise plays a vital role in achieving this goal. It offers a range of positive benefits for cognitive function, regardless of age. However, as our population ages and life expectancy increases, cognitive impairment has become a prevalent issue, often coexisting with age-related neurodegenerative conditions. This can result in devastating consequences such as memory loss, difficulty speaking, and confusion, greatly hindering one's ability to lead an ordinary life. In addition, the decrease in mental capacity has a significant effect on an individual's physical and emotional well-being, greatly reducing their overall level of contentment and causing a significant financial burden for communities. While most current approaches aim to slow the decline of cognition, exercise offers a non-pharmacological, safe, and accessible solution. Its effects on cognition are intricate and involve changes in the brain's neural plasticity, mitochondrial stability, and energy metabolism. Moreover, exercise triggers the release of cytokines, playing a significant role in the body-brain connection and its impact on cognition. Additionally, exercise can influence gene expression through epigenetic mechanisms, leading to lasting improvements in brain function and behavior. Herein, we summarized various genetic and epigenetic mechanisms that can be modulated by exercise in cognitive dysfunction.

Dose-Dependent Effects of Lipopolysaccharide on the Endothelium-Sepsis versus Metabolic Endotoxemia-Induced Cellular Senescence

The endothelium, the innermost cell layer of blood vessels, is not only a physical barrier between the bloodstream and the surrounding tissues but has also essential functions in vascular homeostasis. Therefore, it is not surprising that endothelial dysfunction is associated with most cardiovascular diseases. The functionality of the endothelium is compromised by endotoxemia, the presence of bacterial endotoxins in the bloodstream with the main endotoxin lipopolysaccharide (LPS). Therefore, this review will focus on the effects of LPS on the endothelium. Depending on the LPS concentration, the outcomes are either sepsis or, at lower concentrations, so-called low-dose or metabolic endotoxemia. Sepsis, a life-threatening condition evoked by hyperactivation of the immune response, includes breakdown of the endothelial barrier resulting in failure of multiple organs. A deeper understanding of the underlying mechanisms in the endothelium might help pave the way to new therapeutic options in sepsis treatment to prevent endothelial leakage and fatal septic shock. Low-dose endotoxemia or metabolic endotoxemia results in chronic inflammation leading to endothelial cell senescence, which entails endothelial dysfunction and thus plays a critical role in cardiovascular diseases. The identification of compounds counteracting senescence induction in endothelial cells might therefore help in delaying the onset or progression of age-related pathologies. Interestingly, two natural plant-derived substances, caffeine and curcumin, have shown potential in preventing endothelial cell senescence.

MiR-146b-5p regulates the scavenging effect of GPx-3 on peroxide in papillary thyroid cancer cells

Background

Glutathione peroxidase (GPx) is an important antioxidant enzyme in thyroid follicular cells. Reduced levels of glutathione peroxidase 3 (GPx-3) expression in papillary thyroid cancer (PTC) are associated with poor prognosis. However, the reason for the decreased expression level of GPx-3 in PTC is unclear.

Methods

The expression of GPx-3 in papillary thyroid carcinoma and adjacent normal tissue (n = 18) was detected by Western blotting. Bioinformatics was used to predict the relationship between the level of GPx-3 and gender, age, lymph node metastasis, stage, BRAFV600E mutation, and recurrence-free survival of patients. The possible upstream microRNAs of GPx-3 were analyzed by bioinformatics tools also. We verified the relationship between GPx-3 and upstream microRNA by dual luciferase reporter assay and enzyme-linked immunosorbent assay (ELISA).

Results

The protein level of GPx-3 decreased in PTC, and analysis of public database datasets suggests that its decreased expression may be associated with the BRAFV600E mutation. MiR-146b-5p was significantly overexpressed in PTC. The dual luciferase reporter assay verified the effect of miR-146b-5p on 3'-UTR of GPx-3 mRNA. Knockdown of miR-146b-5p in thyroid cancer cell lines TPC-1 and BCPAP increased GPx-3 expression levels, accompanied by an increase in the conversion of glutathione (GSH) to oxidized glutathione (GSSG).

Conclusions

In conclusion, the level of GPx-3 decreases in papillary thyroid carcinoma and impairs intracellular peroxide clearance, due to the inhibitory effect of miR-146b-5p. The accumulation of intracellular peroxides may contribute to the poor prognosis of thyroid cancer.

Rising Influence of Nanotechnology in Addressing Oxidative Stress-Related Liver Disorders

Reactive oxygen species (ROS) play a significant role in the survival and decline of various biological systems. In liver-related metabolic disorders such as steatohepatitis, ROS can act as both a cause and a consequence. Alcoholic steatohepatitis (ASH) and non-alcoholic steatohepatitis (NASH) are two distinct types of steatohepatitis. Recently, there has been growing interest in using medications that target ROS formation and reduce ROS levels as a therapeutic approach for oxidative stress-related liver disorders. Mammalian systems have developed various antioxidant defenses to protect against excessive ROS generation. These defenses modulate ROS through a series of reactions, limiting their potential impact. However, as the condition worsens, exogenous antioxidants become necessary to control ROS levels. Nanotechnology has emerged as a promising avenue, utilizing nanocomplex systems as efficient nano-antioxidants. These systems demonstrate enhanced delivery of antioxidants to the target site, minimizing leakage and improving targeting accuracy. Therefore, it is essential to explore the evolving field of nanotechnology as an effective means to lower ROS levels and establish efficient therapeutic interventions for oxidative stress-related liver disorders.

Rising Influence of Nanotechnology in Addressing Oxidative Stress-Related Liver Disorders

Reactive oxygen species (ROS) play a significant role in the survival and decline of various biological systems. In liver-related metabolic disorders such as steatohepatitis, ROS can act as both a cause and a consequence. Alcoholic steatohepatitis (ASH) and non-alcoholic steatohepatitis (NASH) are two distinct types of steatohepatitis. Recently, there has been growing interest in using medications that target ROS formation and reduce ROS levels as a therapeutic approach for oxidative stress-related liver disorders. Mammalian systems have developed various antioxidant defenses to protect against excessive ROS generation. These defenses modulate ROS through a series of reactions, limiting their potential impact. However, as the condition worsens, exogenous antioxidants become necessary to control ROS levels. Nanotechnology has emerged as a promising avenue, utilizing nanocomplex systems as efficient nano-antioxidants. These systems demonstrate enhanced delivery of antioxidants to the target site, minimizing leakage and improving targeting accuracy. Therefore, it is essential to explore the evolving field of nanotechnology as an effective means to lower ROS levels and establish efficient therapeutic interventions for oxidative stress-related liver disorders.

Advances in the Functions of Thioredoxin System in Central Nervous System Diseases

Significance: The thioredoxin system comprises thioredoxin (Trx), thioredoxin reductase (TrxR), and nicotinamide adenine dinucleotide phosphate, besides an endogenous Trx inhibitor, the thioredoxin-interacting protein (TXNIP). The Trx system plays critical roles in maintaining the redox homeostasis in the central nervous system (CNS), in which oxidative stress damage is prone to occurrence due to its high-energy demand. Recent Advances: Increasing studies have demonstrated that the expression or activity of Trx/TrxR is usually decreased and that TXNIP expression is increased in patients with CNS diseases, including neurodegenerative diseases, cerebral ischemia, traumatic brain injury, and depression, as well as in their cellular and animal models. The compromise of Trx/TrxR enhances the susceptibility of neurons to related pathological state. Increased TXNIP not only enhances the inhibition of Trx activity, but also activates the NOD-like receptor protein 3 inflammasome, resulting in neuroinflammation in the brain. Critical Issues: In this review, we highlight the sources of oxidative stress in the CNS. The expression and function of the Trx system are summarized in different CNS diseases. This review also mentions that some inducers of Trx show neuroprotection in CNS diseases. Future Directions: Accumulating evidence has demonstrated the important roles of the Trx system in CNS diseases, suggesting that the Trx system may be a promising therapeutic target for CNS diseases. Further study should aim to develop the most effective inducers of Trx and specific inhibitors of TXNIP and to apply them in the clinical trials for the treatment of CNS diseases. Antioxid. Redox Signal. 38, 425-441.

Cytosolic glutaredoxin 1 is upregulated in AMD and controls retinal pigment epithelial cells proliferation via β-catenin

Thioredoxin (Trx) family proteins are key players in redox signaling. Here, we have analyzed glutaredoxin (Grx) 1 and Grx2 in age-related macular degeneration (AMD) and in retinal pigment epithelial (ARPE-19) cells. We hypothesized that these redoxins regulate cellular functions and signaling circuits such as cell proliferation, Wnt signaling and VEGF release that have been correlated to the pathophysiology of AMD. ARPE-19 cells were transfected with specific siRNAs to silence the expression of Grx1 and Grx2 and were analyzed for proliferation/viability, migration capacity, β-catenin activation, and VEGF release. An active site-mutated C-X-X-S Grx1 was utilized to trap interacting proteins present in ARPE-19 cell extracts. In both, AMD retinas and in ARPE-19 cells incubated under hypoxia/reoxygenation conditions, Grx1 showed an increased nuclear localization. Grx1-silenced ARPE-19 cells showed a significantly reduced proliferation and migration rate. Our trapping approach showed that Grx1 interacts with β-catenin in a dithiol-disulfide exchange reaction. Knock-down of Grx1 led to a reduction in both total and active β-catenin levels. These findings add redox control to the regulatory mechanisms of β-catenin signaling in the retinal pigment epithelium and open the door to novel therapeutic approaches in AMD that is currently treated with VEGF-inhibitors.

Potential Role of APEX1 During Ferroptosis

Ferroptosis is a recently discovered category of programmed cell death. It is much different from other types of cell death such as apoptosis, necrosis and autophagy. The main pathological feature of ferroptosis is the accumulation of iron-dependent lipid peroxidation. The typical changes in the morphological features of ferroptosis include cell volume shrinkage and increased mitochondrial membrane area. The mechanisms of ferroptosis may be mainly related to lipid peroxidation accumulation, imbalance in amino acid antioxidant system, and disturbance of iron metabolism. Besides, hypoxia-inducible factor (HIF), nuclear factor-E2-related factor 2 (Nrf2), and p53 pathway have been demonstrated to be involved in ferroptosis. At present, the molecular mechanisms of ferroptosis pathway are still unmapped. In this review, an outlook has been put forward about the crucial role of apurinic/apyrimidinic endodeoxyribonuclease 1 (APEX1) in the regulation of ferroptosis. APEX1 plays an important role in the regulation of intracellular redox balance and can be used as a potential inhibitor of ferroptotic cell death. Bioinformatics analysis indicated that the mRNA level of APEX1 is decreased in cases of ferroptosis triggered by erastin. Besides, it was found that there was a significant correlation between APEX1 and genes in the ferroptosis pathway. We have discussed the possibility to employ APEX1 inducers or inhibitors in the regulation of ferroptosis as a new strategy for the treatment of various human diseases.

Oxidative Stress in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a challenging disease caused by multiple factors, which may partly explain why it still remains an orphan of adequate therapies. This review highlights the interaction between oxidative stress (OS) and disturbed lipid metabolism. Several reactive oxygen species generators, including those produced in the gastrointestinal tract, contribute to the lipotoxic hepatic (and extrahepatic) damage by fatty acids and a great variety of their biologically active metabolites in a “multiple parallel-hit model”. This leads to inflammation and fibrogenesis and contributes to NAFLD progression. The alterations of the oxidant/antioxidant balance affect also metabolism-related organelles, leading to lipid peroxidation, mitochondrial dysfunction, and endoplasmic reticulum stress. This OS-induced damage is at least partially counteracted by the physiological antioxidant response. Therefore, modulation of this defense system emerges as an interesting target to prevent NAFLD development and progression. For instance, probiotics, prebiotics, diet, and fecal microbiota transplantation represent new therapeutic approaches targeting the gut microbiota dysbiosis. The OS and its counter-regulation are under the influence of individual genetic and epigenetic factors as well. In the near future, precision medicine taking into consideration genetic or environmental epigenetic risk factors, coupled with new OS biomarkers, will likely assist in noninvasive diagnosis and monitoring of NAFLD progression and in further personalizing treatments.

Investigation of the antioxidant activity of the peroxidase system of cell nuclei during germination of wheat embryos with different types of resistance to temperature stress

The yield of agricultural crops directly depends on their ability to adapt to a constantly changing environment, the unfavorable climatic conditions of which cause oxidative stress, accompanied by the generation of reactive oxygen species in plant cells, which can cause damage to heteropolymer cell structures, thereby leading to suppression of plant growth and a decrease in productivity grains. It has been shown that the profile of the antioxidant activity of the peroxidase system in histone and non-histone blocks of structures (nucleoplasm, chromatin) of cell nuclei during germination is more pronounced in the cold-resistant variety Mironovskaya 808 (winter) compared to Mironovskaya yarovaya (spring), which correlates with the intensity of growth processes and can be associated with participation in the realization of proliferation and differentiation programs. A direct relationship between the scavenging of ROS and plant resistance to temperature stress, which is often associated with the increased activity of antioxidant enzymes that impart stress resistance to both high and low temperature stress, apparently also exists at the level of the plant cell nucleus.

Investigation of the antioxidant activity of the peroxidase system of cell nuclei during germination of wheat embryos with different types of resistance to temperature stress

The yield of agricultural crops directly depends on their ability to adapt to a constantly changing environment, the unfavorable climatic conditions of which cause oxidative stress, accompanied by the generation of reactive oxygen species in plant cells, which can cause damage to heteropolymer cell structures, thereby leading to suppression of plant growth and a decrease in productivity grains. It has been shown that the profile of the antioxidant activity of the peroxidase system in histone and non-histone blocks of structures (nucleoplasm, chromatin) of cell nuclei during germination is more pronounced in the cold-resistant variety Mironovskaya 808 (winter) compared to Mironovskaya yarovaya (spring), which correlates with the intensity of growth processes and can be associated with participation in the realization of proliferation and differentiation programs. A direct relationship between the scavenging of ROS and plant resistance to temperature stress, which is often associated with the increased activity of antioxidant enzymes that impart stress resistance to both high and low temperature stress, apparently also exists at the level of the plant cell nucleus.

Using DCP-Rho1 as a fluorescent probe to visualize sulfenic acid-containing proteins in living plant cells

Among the biologically relevant reactive oxygen species (ROS), hydrogen peroxide (H₂O₂) has special properties. H₂O₂ can diffuse across membranes, has a low reactivity, and is very stable. Deprotonated cysteine residues in proteins can be oxidized by H₂O₂ into a highly reactive sulfenic acid derivative (-SOH), which can react with another cysteine to form a disulfide. Under higher oxidative stress the sulfenic acid undergo further oxidation to sulfinic acid (Cys-SO₂H), which can subsequently be reduced. The sulfinic acid can be hyperoxidized to sulfonic acid (Cys-SO₃H), whose reduction is irreversible. Formation of sulfenic acids can have a role in sensing oxidative stress, signal transduction, modulating localization and activity to regulate protein functions. Therefore, there is an emerging interest in trying to understand the pool of proteins that result in these sorts of modification in response to oxidative stress. This is known as the sulfenome and several approaches have been developed in animal and plant cells to analyze the sulfenome under different stress responses. These approaches can be proteomic, molecular, immunological (i.e., antibodies), or expressing genetically encoded probes that specifically react to sulfenic modifications. In this chapter, we describe an additional approach that allows visualization of sulfenic modification in vivo. This is newly developed fluorescent probe DCP-Rho1 can be implemented in any plant cell to analyze the sulfenic modification.

The Role and Mechanism of Oxidative Stress and Nuclear Receptors in the Development of NAFLD

The overproduction of reactive oxygen species (ROS) and consequent oxidative stress contribute to the pathogenesis of acute and chronic liver diseases. It is now acknowledged that nonalcoholic fatty liver disease (NAFLD) is characterized as a redox-centered disease due to the role of ROS in hepatic metabolism. However, the underlying mechanisms accounting for these alternations are not completely understood. Several nuclear receptors (NRs) are dysregulated in NAFLD, and have a direct influence on the expression of a set of genes relating to the progress of hepatic lipid homeostasis and ROS generation. Meanwhile, the NRs act as redox sensors in response to metabolic stress. Therefore, targeting NRs may represent a promising strategy for improving oxidation damage and treating NAFLD. This review summarizes the link between impaired lipid metabolism and oxidative stress and highlights some NRs involved in regulating oxidant/antioxidant turnover in the context of NAFLD, shedding light on potential therapies based on NR-mediated modulation of ROS generation and lipid accumulation.

Molecular mechanisms of oxidative stress in asthma

The lungs are exposed to reactive oxygen species oxygen (ROS) produced as a result of inhalation of oxygen, as well as smoke and other air pollutants. Cell metabolism and the NADPH oxidases (Nox) generate low levels of intracellular ROS that act as signal transduction mediators by inducing oxidative modifications of histones, enzymes and transcription factors. Redox signalling is also regulated by localised production and sensing of ROS in mitochondria, the endoplasmic reticulum (ER) and inside the nucleus. Intracellular ROS are maintained at low levels through the action of a battery of enzymatic and non-enzymatic antioxidants. Asthma is a heterogeneous airway inflammatory disease with different immune endotypes; these include atopic or non-atopic Th2 type immune response associated with eosinophilia, or a non-Th2 response associated with neutrophilia. Airway remodelling and hyperresponsiveness accompany the inflammatory response in asthma. Over-production of ROS resulting from infiltrating immune cells, particularly eosinophils and neutrophils, and a concomitant impairment of antioxidant responses lead to development of oxidative stress in asthma. Oxidative stress is augmented in severe asthma and during exacerbations, as well as by air pollution and obesity, and causes oxidative damage of tissues promoting airway inflammation and hyperresponsiveness. Furthermore, deregulated Nox activity, mitochondrial dysfunction, ER stress and/or oxidative DNA damage, resulting from exposure to irritants, inflammatory mediators or obesity, may lead to redox-dependent changes in cell signalling. ROS play a central role in airway epithelium-mediated sensing, development of innate and adaptive immune responses, and airway remodelling and hyperresponsiveness. Nonetheless, antioxidant compounds have proven clinically ineffective as therapeutic agents for asthma, partly due to issues with stability and in vivo metabolism of these compounds. The compartmentalised nature of ROS production and sensing, and the role of ROS in homeostatic responses and in the action of corticosteroids and β2-adrenergic receptor agonists, adds another layer of complexity to antioxidant therapy development. Nox inhibitors and mitochondrial-targeted antioxidants are in clinical development for a number of diseases but they have not yet been investigated in asthma. A better understanding of the complex role of ROS in the pathogenesis of asthma will highlight new opportunities for more targeted and effective redox therapies.

Exercise-Stimulated ROS Sensitive Signaling Pathways in Skeletal Muscle

Physical exercise represents a major challenge to whole-body homeostasis, provoking acute and adaptative responses at the cellular and systemic levels. Different sources of reactive oxygen species (ROS) have been described in skeletal muscle (e.g., NADPH oxidases, xanthine oxidase, and mitochondria) and are closely related to the physiological changes induced by physical exercise through the modulation of several signaling pathways. Many signaling pathways that are regulated by exercise-induced ROS generation, such as adenosine monophosphate-activated protein kinase (AMPK), mitogen activated protein kinase (MAPK), nuclear respiratory factor2 (NRF2), and PGC-1α are involved in skeletal muscle responses to physical exercise, such as increased glucose uptake, mitochondriogenesis, and hypertrophy, among others. Most of these adaptations are blunted by antioxidants, revealing the crucial role played by ROS during and after physical exercise. When ROS generation is either insufficient or exacerbated, ROS-mediated signaling is disrupted, as well as physical exercise adaptations. Thus, an understanding the limit between "ROS that can promote beneficial effects" and "ROS that can promote harmful effects" is a challenging question in exercise biology. The identification of new mediators that cause reductive stress and thereby disrupt exercise-stimulated ROS signaling is a trending on this topic and are covered in this current review.

The effects of low-dose 2-hydroxyethyl methacrylate on apoptosis and survival in human dental pulp cells

BACKGROUND/PURPOSE

2-hydroxyethyl methacrylate (HEMA) is one of the most major components in dentin bonding systems. Uncured HEMA is eluted through the dentin and harmful to pulp cells. The study aimed to investigate the death pattern, morphological change and factors of human dental pulp cells (HDPCs) cultured with low-dose HEMA.

METHODS

HDPCs were cultured with low-dose concentration of HEMA at 0 mM (control), 0.125 mM, 0.25 mM, 1 mM, 2 mM and 4 mM on Day 3 and 5. The cell morphology was observed with F-actin immunocytochemical staining. The flow cytometry was used to analyze the death pattern. NF-κB and Trx-1 were measured using ELISA kits.

RESULTS

The major death pattern was early apoptosis and late apoptosis. The morphological characteristics of apoptosis were observed clearly at 4 mM on Day 3 and Day 5. The phosphorylated NF-κB normalized to total NF-κB protein was significantly higher at 2 mM and 4 mM on Day 5. There was no difference of Trx-1 on Day 3, but significantly higher at 0.25 mM and 1 mM on Day 5. The trend line of phosphorylated NF-κB and Trx-1 showed highly positive correlations with HEMA concentration.

CONCLUSION

The significant cellular morphology characteristics of apoptosis can be observed at higher dose and longer period after exposed to uncured HEMA. The expression of NF-κB was following the ratio of late apoptosis at longer exposure period. Clinically, the remaining dentin thickness should be enough to decrease HEMA concentration and thus to protect pulp cells free from harm.

Octreotide (somatostatin analog) attenuates cardiac ischemia/reperfusion injury via activating nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signaling pathway in rat model of hyperthyroidism

Background

Hyperthyroidism is known to increase the risk of ischemic heart diseases. Octreotide has been reported to attenuate ischemia/reperfusion (I/R) injury. Whether it is useful when ischemic heart disease is accompanied with co-morbidities like hyperthyroidism needs more clarifying. So, this study aimed to explore the effect of octreotide on cardiac I/R injury in hyperthyroid rats and to clarify if Nrf2 activation is involved in this effect. Forty adult female Wistar rats were subdivided into control (euthyroid) (n = 10) and hyperthyroid (n = 30) groups. Rats in hyperthyroid group received l-thyroxine (12 mg/L) in drinking water for 35 days, then were randomly divided into three equal subgroups (n = 10): hyperthyroid control positive group, hyperthyroid octreotide treated group, and hyperthyroid octreotide + Nrf2 inhibitor (brusatol) treated group. Isolated hearts were submitted to I/R and evaluated for cardiac hemodynamics and infarct size. Serum T3 and T4, coronary efflux lactate dehydrogenase (LDH) and creatine kinase-myoglobin binding (CK-MB) and cardiac tissue malondialdehyde (MDA) were estimated. Nrf2- regulated gene expressions of HO-1, SOD, GPx, and catalase were assessed.

Results

Octreotide administration to hyperthyroid rats improved baseline and post-ischemic recovery of cardiac hemodynamics, decreased the high coronary efflux LDH and CK-MB and tissue MDA, reduced infarction size, and upregulated the decreased antioxidative enzymes HO-1, SOD, GPx, and catalase mRNA expressions in the hyperthyroid I/R rat hearts. The Nrf2 inhibitor brusatol reversed the cardioprotective effect of octreotide in hyperthyroid I/R rat hearts.

Conclusion

Octreotide can reduce oxidative stress to effectively alleviate I/R injury in the hyperthyroid rat hearts through upregulation of Nrf2-dependent antioxidative signaling pathways.

Oxidative stress values of tumor core, edge, and healthy thyroid tissue in thyroid masses

PURPOSE

Reactive oxygen radicals play an important role in tumor formation, progression, and invasion. In this study, the aim was to investigate the relationship between the oxidative stress values of tumor core, edge, and healthy thyroid tissue in thyroid tumors.

METHODS

A total of 51 patients with thyroid tumor, 24-malignant, and 27-benign, were included in this study. Samples, measuring 5 × 5 × 5 mm, were taken from the tumor core, edge, and healthy thyroid tissue of the participants. Total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) values were examined. The oxidative stress values of core, edge, and healthy thyroid tissue of all tumors (n = 51) were compared according to the localization. The participants were divided into two groups as malignant (Group 1: Differentiated thyroid cancers) and benign (Group 2: Multinodular goiter). The groups were compared according to tissue localizations.

RESULTS

The TOS value of tumor edge was significantly higher than the values of tumor core and healthy thyroid tissue. The OSI value of tumor edge was significantly higher than the values of tumor core and healthy thyroid tissue. There was no significant difference between Group 1 and Group 2 in terms of TAS, TOS, and OSI values of tumor core. The OSI values in tumor edge and healthy thyroid tissue were significantly higher in Group 1 than in Group 2. There was no significant difference between the groups in terms of TAS and TOS values of tumor edge and healthy thyroid tissue.

CONCLUSION

The oxidative stress values of tumor edge were significantly higher than the tumor core and healthy thyroid tissue values. The oxidative stress values of tumor edge and healthy thyroid tissue were significantly higher in malignant thyroid tumors compared to benign thyroid tumors.

PGC-1α, Inflammation, and Oxidative Stress: An Integrative View in Metabolism

Peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α is a transcriptional coactivator described as a master regulator of mitochondrial biogenesis and function, including oxidative phosphorylation and reactive oxygen species detoxification. PGC-1α is highly expressed in tissues with high energy demands, and it is clearly associated with the pathogenesis of metabolic syndrome and its principal complications including obesity, type 2 diabetes mellitus, cardiovascular disease, and hepatic steatosis. We herein review the molecular pathways regulated by PGC-1α, which connect oxidative stress and mitochondrial metabolism with inflammatory response and metabolic syndrome. PGC-1α regulates the expression of mitochondrial antioxidant genes, including manganese superoxide dismutase, catalase, peroxiredoxin 3 and 5, uncoupling protein 2, thioredoxin 2, and thioredoxin reductase and thus prevents oxidative injury and mitochondrial dysfunction. Dysregulation of PGC-1α alters redox homeostasis in cells and exacerbates inflammatory response, which is commonly accompanied by metabolic disturbances. During inflammation, low levels of PGC-1α downregulate mitochondrial antioxidant gene expression, induce oxidative stress, and promote nuclear factor kappa B activation. In metabolic syndrome, which is characterized by a chronic low grade of inflammation, PGC-1α dysregulation modifies the metabolic properties of tissues by altering mitochondrial function and promoting reactive oxygen species accumulation. In conclusion, PGC-1α acts as an essential node connecting metabolic regulation, redox control, and inflammatory pathways, and it is an interesting therapeutic target that may have significant benefits for a number of metabolic diseases.

Interactions between metabolism and chromatin in plant models

BACKGROUND

One of the fascinating aspects of epigenetic regulation is that it provides means to rapidly adapt to environmental change. This is particularly relevant in the plant kingdom, where most species are sessile and exposed to increasing habitat fluctuations due to global warming. Although the inheritance of epigenetically controlled traits acquired through environmental impact is a matter of debate, it is well documented that environmental cues lead to epigenetic changes, including chromatin modifications, that affect cell differentiation or are associated with plant acclimation and defense priming. Still, in most cases, the mechanisms involved are poorly understood. An emerging topic that promises to reveal new insights is the interaction between epigenetics and metabolism.

SCOPE OF REVIEW

This study reviews the links between metabolism and chromatin modification, in particular histone acetylation, histone methylation, and DNA methylation, in plants and compares them to examples from the mammalian field, where the relationship to human diseases has already generated a larger body of literature. This study particularly focuses on the role of reactive oxygen species (ROS) and nitric oxide (NO) in modulating metabolic pathways and gene activities that are involved in these chromatin modifications. As ROS and NO are hallmarks of stress responses, we predict that they are also pivotal in mediating chromatin dynamics during environmental responses.

MAJOR CONCLUSIONS

Due to conservation of chromatin-modifying mechanisms, mammals and plants share a common dependence on metabolic intermediates that serve as cofactors for chromatin modifications. In addition, plant-specific non-CG methylation pathways are particularly sensitive to changes in folate-mediated one-carbon metabolism. Finally, reactive oxygen and nitrogen species may fine-tune epigenetic processes and include similar signaling mechanisms involved in environmental stress responses in plants as well as animals.

Extracellular vesicle-mediated macrophage activation: An insight into the mechanism of thioredoxin-mediated immune activation

Extracellular vesicles (EVs) generated from redox active anticancer drugs are released into the extracellular environment. These EVs contain oxidized molecules and trigger inflammatory responses by macrophages. Using a mouse model of doxorubicin (DOX)-induced tissue injury, we previously found that the major sources of circulating EVs are from heart and liver, organs that are differentially affected by DOX. Here, we investigated the effects of EVs from cardiomyocytes and those from hepatocytes on macrophage activation. EVs from H9c2 rat cardiomyocytes (H9c2 EVs) and EVs from FL83b mouse hepatocytes (FL83 b EVs) have different levels of protein-bound 4-hydroxynonenal and thus different immunostimulatory effects on mouse RAW264.7 macrophages. H9c2 EVs but not FL83 b EVs induced both pro-inflammatory and anti-inflammatory macrophage activation, mediated by NFκB and Nrf-2 pathways, respectively. DOX enhanced the effects of H9c2 EVs but not FL83 b EVs. While EVs from DOX-treated H9c2 cells (H9c2 DOXEVs) suppressed mitochondrial respiration and increased glycolysis of macrophages, EVs from DOX-treated FL83b cells (FL83b DOXEVs) enhanced mitochondrial reserve capacity. Mechanistically, the different immunostimulatory functions of H9c2 EVs and FL83 b EVs are regulated, in part, by the redox status of the cytoplasmic thioredoxin 1 (Trx1) of macrophages. H9c2 DOXEVs lowered the level of reduced Trx1 in cytoplasm while FL83b DOXEVs did the opposite. Trx1 overexpression alleviated the effect of H9c2 DOXEVs on NFκB and Nrf-2 activation and prevented the upregulation of their target genes. Our findings identify EVs as a novel Trx1-mediated redox mediator of immune response, which greatly enhances our understanding of innate immune responses during cancer therapy.

Redox Systems Biology of Nutrition and Oxidative Stress

Diet and nutrition contribute to both beneficial and harmful aspects of oxidative processes. The harmful processes, termed oxidative stress, occur with many human diseases. Major advances in understanding oxidative stress and nutrition have occurred with broad characterization of dietary oxidants and antioxidants, and with mechanistic studies showing antioxidant efficacy. However, randomized controlled trials in humans with free-radical-scavenging antioxidants and the glutathione precursor N-acetylcysteine have provided limited or inconsistent evidence for health benefits. This, combined with emerging redox theory, indicates that holistic models are needed to understand the interplay of nutrition and oxidative stress. The purpose of this article is to highlight how recent advances in redox theory and the development of new omics tools and data-driven approaches provide a framework for future nutrition and oxidative stress research. Here we describe why a holistic approach is needed to understand the impact of nutrition on oxidative stress and how recent advances in omics and data analysis methods are viable tools for systems nutrition approaches. Based on the extensive research on glutathione and related thiol antioxidant systems, we summarize the advancing framework for diet and oxidative stress in which antioxidant systems are a component of a larger redox network that serves as a responsive interface between the environment and an individual. The feasibility for redox network analysis has been established by experimental models in which dietary factors are systematically varied and oxidative stress markers are linked through integrated omics (metabolome, transcriptome, proteome). With this framework, integrated redox network models will support optimization of diet to protect against oxidative stress and disease.

Oxidative stress in thyroid carcinomas: biological and clinical significance

At physiological concentrations, reactive oxygen species (ROS), including superoxide anions and H2O2, are considered as second messengers that play key roles in cellular functions, such as proliferation, gene expression, host defence and hormone synthesis. However, when they are at supraphysiological levels, ROS are considered potent DNA-damaging agents. Their increase induces oxidative stress, which can initiate and maintain genomic instability. The thyroid gland represents a good model for studying the impact of oxidative stress on genomic instability. Indeed, one particularity of this organ is that follicular thyroid cells synthesise thyroid hormones through a complex mechanism that requires H2O2. Because of their detection in thyroid adenomas and in early cell transformation, both oxidative stress and DNA damage are believed to be neoplasia-preceding events in thyroid cells. Oxidative DNA damage is, in addition, detected in the advanced stages of thyroid cancer, suggesting that oxidative lesions of DNA also contribute to the maintenance of genomic instability during the subsequent phases of tumourigenesis. Finally, ionizing radiation and the mutation of oncogenes, such as RAS and BRAF, play a key role in thyroid carcinogenesis through separate and unique mechanisms: they upregulate the expression of two distinct 'professional' ROS-generating systems, the NADPH oxidases DUOX1 and NOX4, which cause DNA damage that may promote chromosomal instability, tumourigenesis and dedifferentiation.

Dietaryα-lactalbumin induced fatty liver by enhancing nuclear liver X receptorαβ/sterol regulatory element-binding protein-1c/PPARγexpression and minimising PPARα/carnitine palmitoyltransferase-1 expression and AMP-activated protein kinaseαphosphorylation associated with atherogenic dyslipidaemia, insulin resistance and oxidative stress in Balb/c mice

The effect and the role played by dietaryα-lactalbumin (α-LAC) on hepatic fat metabolism are yet to be fully elucidated. We reported previously thatα-LAC intake induced atherogenic dyslipidaemia in Balb/c mice. The aim of the present study was to investigate if this atherogenic effect could be due to a possibleα-LAC-induced hepatic steatosis. We examine the ability of dietaryα-LAC to induce liver steatosis, identifying the molecular mechanisms underlying hepatic lipid metabolism in association with the lipid profile, peripheral insulin resistance (IR) and changes in the hepatic oxidative environment. Male Balb/c mice (n6) were fed with diets containing either chow or 14 %α-LAC for 4 weeks. Theα-LAC-fed mice developed abdominal adiposity and IR. Moderate liver steatosis with increased TAG and NEFA contents was correlated with atherogenic dyslipidaemia. There was increased nuclear expression of liver X receptorαβ(LXRαβ), sterol regulatory element-binding protein-1c (SREBP-1c) and PPARγtranscription factors and of the cytosolic enzymes acetyl-CoA carboxylase 1 (ACC1) and fatty acid synthase involved in the hepaticde novolipogenesis. The opposite was found for the nuclear receptor PPARαand the mitochondrial enzyme carnitine palmitoyltransferase-1 (CPT-1), leading to reduced fatty acidβ-oxidation (FAO). These changes were associated with a significant decrease in both p-Thr172-AMP-activated protein kinaseα(AMPKα) (inactivation) and p-Ser79-ACC1 (activation) and with a more oxidative liver environment increasing lipid peroxidation and protein oxidation and reducing GSH:GSSG ratio in theα-LAC-fed mice. In conclusion, 4 weeks of 14 %α-LAC feeding induced liver steatosis associated with atherogenic dyslipidaemia, IR and oxidative stress by enhancing nuclear LXRαβ/SREBP-1c/PPARγexpression and diminishing PPARα/CPT-1 expression and AMPKαphosphorylation shifting the hepatic FAO toward fatty acid synthesis in Balb/c mice.

Thioredoxin system-mediated regulation of mutant Kras associated pancreatic neoplasia and cancer

Peroxiredoxin-1 (Prdx1), a member of the thioredoxin (Txn) system, is overexpressed and correlates with poor prognosis in pancreatic cancer patients and can suppress Kras signaling through redox-mediated inhibition of ERK and AKT in lung and breast cancer. Its redox function is maintained by Txn and sulfiredoxin (Srxn), and its tumor promoting functions are activated by post-translational modification. We studied the role of the Txn system in pancreatic neoplasia and cancer by determining how it regulates the phosphorylation of Kras effectors and by determining its association with patient survival. We found that elevated Prdx1 nuclear localization significantly correlated with better patient survival. Our data also demonstrate that the expression of the Txn system is dysregulated, with elevated Prdx1 expression and significantly decreased Txn and Srxn expression in pancreatic lesions of targeted mutant Kras mouse models. This correlated with distinct differences in the interconversion of Prdx1 oligomers that affect its ability to regulate ERK and AKT phosphorylation. Our data also suggest that Prdx1 post-translational modification and oligomerization suppress Prdx1 mediated redox regulation of ERK phosphorylation. We observed distinct differences in Txn expression and in the ability of pTyr-Prdx1 to bind to pERK in a PanIN model of pancreatic neoplasia as compared to an IPMN model, indicating a distinct difference in the function of post-translationally modified Prdx1 in cells with less Txn expression. Modified Txn system function and post-translational regulation may therefore play a significant role in pancreatic tumorigenesis by altering Kras effector phosphorylation and inhibiting the tumor suppressive redox functions of Prdx1.

Lipid oxidation products in the pathogenesis of non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the major public health challenge for hepatologists in the twenty-first century. NAFLD comprises a histological spectrum ranging from simple steatosis or fatty liver, to steatohepatitis, fibrosis, and cirrhosis. It can be categorized into two principal phenotypes: (1) non-alcoholic fatty liver (NAFL), and (2) non-alcoholic steatohepatitis (NASH). The mechanisms of NAFLD progression consist of lipid homeostasis alterations, redox unbalance, insulin resistance, and inflammation in the liver. Even though several studies show an association between the levels of lipid oxidation products and disease state, experimental evidence suggests that compounds such as reactive aldehydes and cholesterol oxidation products, in addition to representing hallmarks of hepatic oxidative damage, may behave as active players in liver dysfunction and the development of NAFLD. This review summarizes the processes that contribute to the metabolic alterations occurring in fatty liver that produce fatty acid and cholesterol oxidation products in NAFLD, with a focus on inflammation, the control of insulin signalling, and the transcription factors involved in lipid metabolism.

Regulation of Transcription Factors by Reactive Oxygen Species and Nitric Oxide in Vascular Physiology and Pathology

SIGNIFICANCE

Cardiovascular diseases are the main cause of death worldwide and pose an immense economical burden. In most cases, the underlying problem is vascular occlusion by atherosclerotic plaques. Importantly, different cell types of the vascular wall and the immune system play crucial roles in atherosclerosis at different stages of the disease. Furthermore, atherosclerosis and conditions recognized as risk factors are characterized by a reduced availability of the vasoprotective molecule nitric oxide and an increase in reactive oxygen species, so-called oxidative stress. Transcription factors function as intracellular signal integrators and relays and thus, play a central role in cellular responses to changing conditions. Recent Advances: Work on specific transcriptional regulators has uncovered many of their functions and the upstream pathways modulating their activity in response to reactive oxygen and nitrogen species. Here, we have reviewed for a few selected examples how this can contribute not only to protection against atherosclerosis development but also to disease progression and the occurrence of clinical manifestations, such as plaque rupture.

CRITICAL ISSUES

Transcription factors have pleiotropic outputs and often also divergent functions in different cell types and tissues. Thus, in light of potential severe adverse side effects, a global activation or inhibition of particular transcriptions factors does not seem a feasible therapeutic option.

FUTURE DIRECTIONS

A further in-depth characterization of the cell- and stage-specific actions and regulation of transcription factors in atherosclerosis with respect to protein-protein interactions and target genes could open up new avenues for prevention or therapeutic interventions in this vascular disease. Antioxid. Redox Signal. 26, 679-699.

The Anti-Apoptotic Properties of APEX1 in the Endothelium Require the First 20 Amino Acids and Converge on Thioredoxin-1

The APEX nuclease (multifunctional DNA repair enzyme) 1 (APEX1) has a disordered N-terminus, a redox, and a DNA repair domain. APEX1 has anti-apoptotic properties, which have been linked to both domains depending on cell type and experimental conditions.

AIMS

As protection against apoptosis is a hallmark of vessel integrity, we wanted to elucidate whether APEX1 acts anti-apoptotic in primary human endothelial cells and, if so, what the underlying mechanisms are.

RESULTS

APEX1 inhibits apoptosis in endothelial cells by reducing Cathepsin D (CatD) cleavage, potentially by binding to the unprocessed form. Diminished CatD activation results in increased Thioredoxin-1 protein levels leading to reduced Caspase 3 activation. Consequently, apoptosis rates are decreased. This depends on the first twenty amino acids in APEX1, because APEX1 (21-318) induces CatD activity, decreases Thioredoxin-1 protein levels, and, thus, increases Caspase 3 activity and apoptosis. Along the same lines, APEX1 (1-20) inhibits Caspase 3 cleavage and apoptosis. Furthermore, re-expression of Thioredoxin-1 via lentiviral transduction rescues endothelial cells from APEX1 (21-318)-induced apoptosis. In an in vivo model of restenosis, which is characterized by oxidative stress, endothelial activation, and smooth muscle cell proliferation, Thioredoxin-1 protein levels are reduced in the endothelium of the carotids.

INNOVATION

APEX1 acts anti-apoptotic in endothelial cells. This anti-apoptotic effect depends on the first 20 amino acids of APEX1.

CONCLUSION

As proper function of the endothelium during life span is a hallmark for individual health span, a detailed characterization of the functions of the APEX1N-terminus is required to understand all its cellular properties. Antioxid. Redox Signal. 26, 616-629.

Nuclear Factor (Erythroid-Derived 2)-Like 2 and Thioredoxin-1 in Atherosclerosis and Ischemia/Reperfusion Injury in the Heart

SIGNIFICANCE

Redox signaling is one of the key elements involved in cardiovascular diseases. Two important molecules are the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and the oxidoreductase thioredoxin-1 (Trx-1). Recent Advances: During the previous years, a lot of studies investigated Nrf2 and Trx-1 as protective proteins in cardiovascular disorders. Moreover, post-translational modifications of those molecules were identified that play an important role in the cardiovascular system. This review will summarize changes in the vasculature in atherosclerosis and ischemia reperfusion injury of the heart and the newest findings achieved with Nrf2 and Trx-1 therein. Interestingly, Nrf2 and Trx-1 can act together as well as independently of each other in protection against atherosclerosis and ischemia and reperfusion injury.

CRITICAL ISSUES

In principle, pharmacological activation of a transcription factor-like Nrf2 can be dangerous, since a transcription regulator has multiple targets and the pleiotropic effects of such activation should not be ignored. Moreover, overactivation of Nrf2 as well as long-term treatment with Trx-1 could be deleterious for the cardiovascular system.

FUTURE DIRECTIONS

Therefore, the length of treatment with Nrf2 activators and/or Trx-1 has first to be studied in more detail in cardiovascular disorders. Moreover, a combination of Nrf2 activators and Trx-1 should be investigated and taken into consideration. Antioxid. Redox Signal. 26, 630-644.

Plant Phenols and Autophagy

Many plant phenols (stilbenes, curcumins, catechins, flavonoids, etc.) are effective antioxidants and protect cells during oxidative stress. Extensive clinical studies on the potential of phenolic compounds for treatment of cardiovascular, neurodegenerative, oncological, and inflammatory diseases are now being conducted. In addition to direct antioxidant effect, plant phenols may provide a protective effect via activation of the Keap1/Nrf2/ARE redox-sensitive signaling system and regulation of autophagy. In this review, mechanisms of effects of the most common plant phenols on autophagy are presented.

NADPH oxidases: new actors in thyroid cancer?

Hydrogen peroxide (H2O2) is a crucial substrate for thyroid peroxidase, a key enzyme involved in thyroid hormone synthesis. However, as a potent oxidant, H2O2 might also be responsible for the high level of oxidative DNA damage observed in thyroid tissues, such as DNA base lesions and strand breakages, which promote chromosomal instability and contribute to the development of tumours. Although the role of H2O2 in thyroid hormone synthesis is well established, its precise mechanisms of action in pathological processes are still under investigation. The NADPH oxidase/dual oxidase family are the only oxidoreductases whose primary function is to produce reactive oxygen species. As such, the function and expression of these enzymes are tightly regulated. Thyrocytes express dual oxidase 2, which produces most of the H2O2 for thyroid hormone synthesis. Thyrocytes also express dual oxidase 1 and NADPH oxidase 4, but the roles of these enzymes are still unknown. Here, we review the structure, expression, localization and function of these enzymes. We focus on their potential role in thyroid cancer, which is characterized by increased expression of these enzymes.

Global Plant Stress Signaling: Reactive Oxygen Species at the Cross-Road

Current technologies have changed biology into a data-intensive field and significantly increased our understanding of signal transduction pathways in plants. However, global defense signaling networks in plants have not been established yet. Considering the apparent intricate nature of signaling mechanisms in plants (due to their sessile nature), studying the points at which different signaling pathways converge, rather than the branches, represents a good start to unravel global plant signaling networks. In this regard, growing evidence shows that the generation of reactive oxygen species (ROS) is one of the most common plant responses to different stresses, representing a point at which various signaling pathways come together. In this review, the complex nature of plant stress signaling networks will be discussed. An emphasis on different signaling players with a specific attention to ROS as the primary source of the signaling battery in plants will be presented. The interactions between ROS and other signaling components, e.g., calcium, redox homeostasis, membranes, G-proteins, MAPKs, plant hormones, and transcription factors will be assessed. A better understanding of the vital roles ROS are playing in plant signaling would help innovate new strategies to improve plant productivity under the circumstances of the increasing severity of environmental conditions and the high demand of food and energy worldwide.

Nuclear thiol redox systems in plants

Thiol-disulfide redox regulation is essential for many cellular functions in plants. It has major roles in defense mechanisms, maintains the redox status of the cell and plays structural, with regulatory roles for many proteins. Although thiol-based redox regulation has been extensively studied in subcellular organelles such as chloroplasts, it has been much less studied in the nucleus. Thiol-disulfide redox regulation is dependent on the conserved redox proteins, glutathione/glutaredoxin (GRX) and thioredoxin (TRX) systems. We first focus on the functions of glutathione in the nucleus and discuss recent data concerning accumulation of glutathione in the nucleus. We also provide evidence that glutathione reduction is potentially active in the nucleus. Recent data suggests that the nucleus is enriched in specific GRX and TRX isoforms. We discuss the biochemical and molecular characteristics of these isoforms and focus on genetic evidences for their potential nuclear functions. Finally, we make an overview of the different thiol-based redox regulated proteins in the nucleus. These proteins are involved in various pathways including transcriptional regulation, metabolism and signaling.

The Sub1 nuclear protein protects DNA from oxidative damage

Reactive oxygen species are a by-product of aerobic metabolism that can damage lipid, proteins, and nucleic acids. Oxidative damage to DNA is especially critical, because it can lead to cell death or mutagenesis. Previously we reported that the yeast sub1 deletion mutant is sensitive to hydrogen peroxide treatment and that the human SUB1 can complement the sensitivity of the yeast sub1 mutant. In this study, we find that Sub1 protects DNA from oxidative damage in vivo and in vitro. We demonstrate that transcription of SUB1 mRNA is induced by oxidative stress and that the sub1Δ mutant has an increased number of chromosomal DNA strand breaks after peroxide treatment. We further demonstrate that purified Sub1 protein can protect DNA from oxidative damage in vitro, using the metal ion catalyzed oxidation assay.

Dynamic Redox Regulation of IL-4 Signaling

Quantifying the magnitude and dynamics of protein oxidation during cell signaling is technically challenging. Computational modeling provides tractable, quantitative methods to test hypotheses of redox mechanisms that may be simultaneously operative during signal transduction. The interleukin-4 (IL-4) pathway, which has previously been reported to induce reactive oxygen species and oxidation of PTP1B, may be controlled by several other putative mechanisms of redox regulation; widespread proteomic thiol oxidation observed via 2D redox differential gel electrophoresis upon IL-4 treatment suggests more than one redox-sensitive protein implicated in this pathway. Through computational modeling and a model selection strategy that relied on characteristic STAT6 phosphorylation dynamics of IL-4 signaling, we identified reversible protein tyrosine phosphatase (PTP) oxidation as the primary redox regulatory mechanism in the pathway. A systems-level model of IL-4 signaling was developed that integrates synchronous pan-PTP oxidation with ROS-independent mechanisms. The model quantitatively predicts the dynamics of IL-4 signaling over a broad range of new redox conditions, offers novel hypotheses about regulation of JAK/STAT signaling, and provides a framework for interrogating putative mechanisms involving receptor-initiated oxidation.

Incomplete reduction of oxygen during respiration results in the formation of highly reactive molecules known as reactive oxygen species (ROS) that react indiscriminately with cellular components and adversely affect cellular function. For a long time ROS were thought solely to be undesirable byproducts of respiration. Indeed, high levels of ROS are associated with a number of diseases. Despite these facts, antioxidants, agents that neutralize ROS, have not shown any clinical benefits when used as oral supplements. This paradox is partially explained by discoveries over the last two decades demonstrating that ROS are not always detrimental and may be essential for controlling physiological processes like cell signaling. However, the mechanisms by which ROS react with biomolecules are not well understood. In this work we have combined biological experiments with novel computational methods to identify the most important mechanisms of ROS-mediated regulation in the IL-4 signaling pathway of the immune system. We have also developed a detailed computer model of the IL-4 pathway and its regulation by ROS dependent and independent methods. Our work enhances the understanding of principles underlying regulation of cell signaling by ROS and has potential implications in advancing therapeutic methods targeting ROS and their adverse effects.

Nuclear Nox4 Role in Stemness Power of Human Amniotic Fluid Stem Cells

Human amniotic fluid stem cells (AFSC) are an attractive source for cell therapy due to their multilineage differentiation potential and accessibility advantages. However the clinical application of human stem cells largely depends on their capacity to expand in vitro, since there is an extensive donor-to-donor heterogeneity. Reactive oxygen species (ROS) and cellular oxidative stress are involved in many physiological and pathophysiological processes of stem cells, including pluripotency, proliferation, differentiation, and stress resistance. The mode of action of ROS is also dependent on the localization of their target molecules. Thus, the modifications induced by ROS can be separated depending on the cellular compartments they affect. NAD(P)H oxidase family, particularly Nox4, has been known to produce ROS in the nucleus. In the present study we show that Nox4 nuclear expression (nNox4) depends on the donor and it correlates with the expression of transcription factors involved in stemness regulation, such as Oct4, SSEA-4, and Sox2. Moreover nNox4 is linked with the nuclear localization of redox sensitive transcription factors, as Nrf2 and NF-κB, and with the differentiation potential. Taken together, these results suggest that nNox4 regulation may have important effects in stem cell capability through modulation of transcription factors and DNA damage.

Steatosis-induced proteins adducts with lipid peroxidation products and nuclear electrophilic stress in hepatocytes

Accumulating evidence suggests that fatty livers are particularly more susceptible to several pathological conditions, including hepatic inflammation, cirrhosis and liver cancer. However the exact mechanism of such susceptibility is still largely obscure. The current study aimed to elucidate the effect of hepatocytes lipid accumulation on the nuclear electrophilic stress. Accumulation of intracellular lipids was significantly increased in HepG2 cells incubated with fatty acid (FA) complex (1 mM, 2:1 oleic and palmitic acids). In FA-treated cells, lipid droplets were localized around the nucleus and seemed to induce mechanical force, leading to the disruption of the nucleus morphology. Level of reactive oxygen species (ROS) was significantly increased in FA-loaded cells and was further augmented by treatment with moderate stressor (CoCl₂). Increased ROS resulted in formation of reactive carbonyls (aldehydes and ketones, derived from lipid peroxidation) with a strong perinuclear accumulation. Mass-spectroscopy analysis indicated that lipid accumulation per-se can results in modification of nuclear protein by reactive lipid peroxidation products (oxoLPP). 235 Modified proteins involved in transcription regulation, splicing, protein synthesis and degradation, DNA repair and lipid metabolism were identified uniquely in FA-treated cells. These findings suggest that steatosis can affect nuclear redox state, and induce modifications of nuclear proteins by reactive oxoLPP accumulated in the perinuclear space upon FA-treatment.

•

Effects of fatty acids on modification of nuclear proteins in hepatocytes was studied.

•

Lipid accumulation was associated with abnormal nuclear morphology.

•

Lipid accumulation promoted mitochondrial activity and enhanced ROS generation.

•

Nuclear proteins were modified by lipid peroxidation products.

•

Data suggest nuclear stress as a mechanism for fatty liver disease progression.

Identification of novel nuclear targets of human thioredoxin 1

The dysregulation of protein oxidative post-translational modifications has been implicated in stress-related diseases. Trx1 is a key reductase that reduces specific disulfide bonds and other cysteine post-translational modifications. Although commonly in the cytoplasm, Trx1 can also modulate transcription in the nucleus. However, few Trx1 nuclear targets have been identified because of the low Trx1 abundance in the nucleus. Here, we report the large-scale proteomics identification of nuclear Trx1 targets in human neuroblastoma cells using an affinity capture strategy wherein a Trx1C35S mutant is expressed. The wild-type Trx1 contains a conserved C32XXC35 motif, and the C32 thiol initiates the reduction of a target disulfide bond by forming an intermolecular disulfide with one of the oxidized target cysteines, resulting in a transient Trx1-target protein complex. The reduction is rapidly consummated by the donation of a C35 proton to the target molecule, forming a Trx1 C32-C35 disulfide, and results in the concurrent release of the target protein containing reduced thiols. By introducing a point mutation (C35 to S35) in Trx1, we ablated the rapid dissociation of Trx1 from its reduction targets, thereby allowing the identification of 45 putative nuclear Trx1 targets. Unexpectedly, we found that PSIP1, also known as LEDGF, was sensitive to both oxidation and Trx1 reduction at Cys 204. LEDGF is a transcription activator that is vital for regulating cell survival during HIV-1 infection. Overall, this study suggests that Trx1 may play a broader role than previously believed that might include regulating transcription, RNA processing, and nuclear pore function in human cells.

The Enzymatic Antioxidant System of Human Spermatozoa

The ejaculated spermatozoon, as an aerobic cell, must fight against toxic levels of reactive oxygen species (ROS) generated by its own metabolism but also by other sources such as abnormal spermatozoa, chemicals and toxicants, or the presence of leukocytes in semen. Mammalian spermatozoa are extremely sensitive to oxidative stress, a condition occurring when there is a net increase in ROS levels within the cell. Opportunely, this specialized cell has a battery of antioxidant enzymes (superoxide dismutase, peroxiredoxins, thioredoxins, thioredoxins reductases, and glutathione s-transferases) working in concert to assure normal sperm function. Any impairment of the antioxidant enzymatic activities will promote severe oxidative damage which is observed as plasma membrane lipid peroxidation, oxidation of structural proteins and enzymes, and oxidation of DNA bases that lead to abnormal sperm function. Altogether, these damages occurring in spermatozoa are associated with male infertility. The present review contains a description of the enzymatic antioxidant system of the human spermatozoon and a reevaluation of the role of its different components and highlights the necessity of sufficient supply of reducing agents (NADPH and reduced glutathione) to guarantee normal sperm function.

Nuclear Nox4-derived reactive oxygen species in myelodysplastic syndromes

A role for intracellular ROS production has been recently implicated in the pathogenesis and progression of a wide variety of neoplasias. ROS sources, such as NAD(P)H oxidase (Nox) complexes, are frequently activated in AML (acute myeloid leukemia) blasts and strongly contribute to their proliferation, survival, and drug resistance. Myelodysplastic syndromes (MDS) comprise a heterogeneous group of disorders characterized by ineffective hematopoiesis, with an increased propensity to develop AML. The molecular basis for MDS progression is unknown, but a key element in MDS disease progression is the genomic instability. NADPH oxidases are now recognized to have specific subcellular localizations, this targeting to specific compartments for localized ROS production. Local Nox-dependent ROS production in the nucleus may contribute to the regulation of redox-dependent cell growth, differentiation, senescence, DNA damage, and apoptosis. We observed that Nox1, 2, and 4 isoforms and p22phox and Rac1 subunits are expressed in MDS/AML cell lines and MDS samples, also in the nuclear fractions. Interestingly, Nox4 interacts with ERK and Akt1 within nuclear speckle domain, suggesting that Nox4 could be involved in regulating gene expression and splicing factor activity. These data contribute to the elucidation of the molecular mechanisms used by nuclear ROS to drive MDS evolution to AML.

Glutaredoxin-1 up-regulation induces soluble vascular endothelial growth factor receptor 1, attenuating post-ischemia limb revascularization

Glutaredoxin-1 (Glrx) is a cytosolic enzyme that regulates diverse cellular function by removal of GSH adducts from S-glutathionylated proteins including signaling molecules and transcription factors. Glrx is up-regulated during inflammation and diabetes, and Glrx overexpression inhibits VEGF-induced EC migration. The aim was to investigate the role of up-regulated Glrx in EC angiogenic capacities and in vivo revascularization in the setting of hind limb ischemia. Glrx-overexpressing EC from Glrx transgenic (TG) mice showed impaired migration and network formation and secreted higher levels of soluble VEGF receptor 1 (sFlt), an antagonizing factor to VEGF. After hind limb ischemia surgery Glrx TG mice demonstrated impaired blood flow recovery, associated with lower capillary density and poorer limb motor function compared with wild type littermates. There were also higher levels of anti-angiogenic sFlt expression in the muscle and plasma of Glrx TG mice after surgery. Noncanonical Wnt5a is known to induce sFlt. Wnt5a was highly expressed in ischemic muscles and EC from Glrx TG mice, and exogenous Wnt5a induced sFlt expression and inhibited network formation in human microvascular EC. Adenoviral Glrx-induced sFlt in EC was inhibited by a competitive Wnt5a inhibitor. Furthermore, Glrx overexpression removed GSH adducts on p65 in ischemic muscle and EC and enhanced NF-κB activity, which was responsible for Wnt5a-sFlt induction. Taken together, up-regulated Glrx induces sFlt in EC via NF-κB-dependent Wnt5a, resulting in attenuated revascularization in hind limb ischemia. The Glrx-induced sFlt explains part of the mechanism of redox-regulated VEGF signaling.

To breathe or not to breathe: the haematopoietic stem/progenitor cells dilemma

Adult haematopoietic stem/progenitor cells (HSPCs) constitute the lifespan reserve for the generation of all the cellular lineages in the blood. Although massive progress in identifying the cluster of master genes controlling self-renewal and multipotency has been achieved in the past decade, some aspects of the physiology of HSPCs still need to be clarified. In particular, there is growing interest in the metabolic profile of HSPCs in view of their emerging role as determinants of cell fate. Indeed, stem cells and progenitors have distinct metabolic profiles, and the transition from stem to progenitor cell corresponds to a critical metabolic change, from glycolysis to oxidative phosphorylation. In this review, we summarize evidence, reported in the literature and provided by our group, highlighting the peculiar ability of HSPCs to adapt their mitochondrial oxidative/bioenergetic metabolism to survive in the hypoxic microenvironment of the endoblastic niche and to exploit redox signalling in controlling the balance between quiescence versus active cycling and differentiation. Especial prominence is given to the interplay between hypoxia inducible factor-1, globins and NADPH oxidases in managing the mitochondrial dioxygen-related metabolism and biogenesis in HSPCs under different ambient conditions. A mechanistic model is proposed whereby 'mitochondrial differentiation' is a prerequisite in uncommitted stem cells, paving the way for growth/differentiation factor-dependent processes. Advancing the understanding of stem cell metabolism will, hopefully, help to (i) improve efforts to maintain, expand and manipulate HSPCs ex vivo and realize their potential therapeutic benefits in regenerative medicine; (ii) reprogramme somatic cells to generate stem cells; and (iii) eliminate, selectively, malignant stem cells.

LINKED ARTICLES

This article is part of a themed section on Emerging Therapeutic Aspects in Oncology. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.169.issue-8.

Cross Talk between Two Antioxidant Systems, Thioredoxin and DJ-1: Consequences for Cancer

Oxidative stress, which is associated with an increased concentration of reactive oxygen species (ROS), is involved in the pathogenesis of numerous diseases including cancer. In response to increased ROS levels, cellular antioxidant molecules such as thioredoxin, peroxiredoxins, glutaredoxins, DJ-1, and superoxide dismutases are upregulated to counteract the detrimental effect of ROS. However, cancer cells take advantage of upregulated antioxidant molecules for protection against ROS-induced cell damage. This review focuses on two antioxidant systems, Thioredoxin and DJ-1, which are upregulated in many human cancer types, correlating with tumour proliferation, survival, and chemo-resistance. Thus, both of these antioxidant molecules serve as potential molecular targets to treat cancer. However, targeting one of these antioxidants alone may not be an effective anti-cancer therapy. Both of these antioxidant molecules are interlinked and act on similar downstream targets such as NF-κβ, PTEN, and Nrf2 to exert cytoprotection. Inhibiting either thioredoxin or DJ-1 alone may allow the other antioxidant to activate downstream signalling cascades leading to tumour cell survival and proliferation. Targeting both thioredoxin and DJ-1 in conjunction may completely shut down the antioxidant defence system regulated by these molecules. This review focuses on the cross-talk between thioredoxin and DJ-1 and highlights the importance and consequences of targeting thioredoxin and DJ-1 together to develop an effective anti-cancer therapeutic strategy.

Free radical biology for medicine: learning from nonalcoholic fatty liver disease

Reactive oxygen species, when released under controlled conditions and limited amounts, contribute to cellular proliferation, senescence, and survival by acting as signaling intermediates. In past decades there has been an epidemic diffusion of nonalcoholic fatty liver disease (NAFLD) that represents the result of the impairment of lipid metabolism, redox imbalance, and insulin resistance in the liver. To date, most studies and reviews have been focused on the molecular mechanisms by which fatty liver progresses to steatohepatitis, but the processes leading toward the development of hepatic steatosis in NAFLD are not fully understood yet. Several nuclear receptors, such as peroxisome proliferator-activated receptors (PPARs) α/γ/δ, PPARγ coactivators 1α and 1β, sterol-regulatory element-binding proteins, AMP-activated protein kinase, liver-X-receptors, and farnesoid-X-receptor, play key roles in the regulation of lipid homeostasis during the pathogenesis of NAFLD. These nuclear receptors may act as redox sensors and may modulate various metabolic pathways in response to specific molecules that act as ligands. It is conceivable that a redox-dependent modulation of lipid metabolism, nuclear receptor-mediated, could cause the development of hepatic steatosis and insulin resistance. Thus, this network may represent a potential therapeutic target for the treatment and prevention of hepatic steatosis and its progression to steatohepatitis. This review summarizes the redox-dependent factors that contribute to metabolism alterations in fatty liver with a focus on the redox control of nuclear receptors in normal liver as well as in NAFLD.

Regulation of the human thioredoxin gene promoter and its key substrates: a study of functional and putative regulatory elements

BACKGROUND

The thioredoxin system maintains redox balance through the action of thioredoxin and thioredoxin reductase. Thioredoxin regulates the activity of various substrates, including those that function to counteract cellular oxidative stress. These include the peroxiredoxins, methionine sulfoxide reductase A and specific transcription factors. Of particular relevance is Redox Factor-1, which in turn activates other redox-regulated transcription factors.

SCOPE OF REVIEW

Experimentally defined transcription factor binding sites in the human thioredoxin and thioredoxin reductase gene promoters together with promoters of the major thioredoxin system substrates involved in regulating cellular redox status are discussed. An in silico approach was used to identify potential putative binding sites for these transcription factors in all of these promoters.

MAJOR CONCLUSIONS

Our analysis reveals that many redox gene promoters contain the same transcription factor binding sites. Several of these transcription factors are in turn redox regulated. The ARE is present in several of these promoters and is bound by Nrf2 during various oxidative stress stimuli to upregulate gene expression. Other transcription factors also bind to these promoters during the same oxidative stress stimuli, with this redundancy supporting the importance of the antioxidant response. Putative transcription factor sites were identified in silico, which in combination with specific regulatory knowledge for that gene promoter may inform future experiments.

GENERAL SIGNIFICANCE

Redox proteins are involved in many cellular signalling pathways and aberrant expression can lead to disease or other pathological conditions. Therefore understanding how their expression is regulated is relevant for developing therapeutic agents that target these pathways.

Interacting with thioredoxin-1--disease or no disease?

SIGNIFICANCE

Many cardiovascular disorders are accompanied by a deregulated cellular redox balance resulting in elevated levels of intracellular reactive oxygen species (ROS). One major antioxidative cellular molecule is thioredoxin-1 (Trx-1). Its indispensability is demonstrated by the embryonic lethality of Trx-1 deficient mice. Trx-1 is ubiquitously expressed in cells and has numerous, diverse functions. It not only reduces oxidized proteins or, together with peroxiredoxins, detoxifies H(2)O(2), but also binds to several proteins and thereby regulates their functions. The interaction partners of Trx-1 differ depending on its localization in the cytosol or in the nucleus.

RECENT ADVANCES/CRITICAL ISSUES

Over the past decade it has become clear that Trx-1 is not only critical for tumor functions, which has resulted in therapeutic approaches targeting this protein, but also essential for proper functions of the vasculature and the heart. Changes in post-translational modifications of Trx-1 or in its interactions with other proteins can lead to a switch from a physiologic state of cells and organs to diverse pathologies. This review provides insights into the role of Trx-1 in different physiological situations and cardiac hypertrophy, ischemia reperfusion injury, heart failure, atherosclerosis, and diabetes mellitus type 2, underscoring the central role of Trx-1 in cardiovascular health and disease.

FUTURE DIRECTIONS

Thus, the manipulation of Trx-1 activity in the heart and/or vasculature, for example, by small molecules, seems to be a promising therapeutic option in cardiovascular diseases, as general anti-oxidant treatments would not take into account interactions of Trx-1 with other proteins and also eliminate vital ROS.